Data traffic on optical transmission lines is constantly increasing owing to the increase in the channel-bit width in time multiplex and the number of channels in wavelength multiplex. Because of the increased load on transmission lines, errors are being increasingly noticed in the transmission line and lead to transmission errors. A demand therefore exists for effective methods and devices to monitor optical transmission lines.
At the present time, when there are problems on a transmission line, the transmission lines are generally briefly interrupted in order to be able to connect corresponding measurement devices by which a transmission signal can be coupled into the transmission line in order to test the transmission line. A fraction of the transmitted signal can also be coupled out of line in order to test the transmission line. Continuous or at least uninterrupted coupling is not possible here.
A monitoring system already exists, available from the CIENA Corporation under the name WaveWatcher®, which permits continuous monitoring of an optical network. However, this is a relatively costly system with a network element manager, an optical service channel and an element management system embedded in an optical network. The system monitors, measures and stores the status and operation method of each module in the system. A standard data communications network is used, which is supported by the optical service channel, in order to process management information about the system. The data communications network permits remote access and remote control of network management elements. The drawback of this system is that it is relatively costly.
A system for monitoring optical networks is also available from Lucent Technologies, which is used to supervise the configuration, performance, reliability and other parameters of an optical network at the network management level. This system determines the components that are involved when an error occurs in the network. The operator can then decide what should be done with these components, and he can inform the user of these circuits. This system is also relatively expensive.
As a result, the underlying objective of the present invention is to provide continuous monitoring of an optical transmission line or an optical network by the simplest possible means.